The invention relates to preparations (Zu) based on water and/or organic solvents and their use as a finish on flat materials. On application the preparations give the treated flat materials durable oil- and water-repellent properties and a soft hand.
It is known that flat materials are finished using water- or solvent-based preparations of silicone oils, paraffins, fluorocarbon (FC) polymers and other additives that endow the finished flat material with hydrophobic effects in order that the flat material may in use be able to meet the challenge of exposures to rain, splashed water or moisture. Tent fabrics, for instance, are treated with aqueous emulsions of paraffins, metal soaps and also silicic acid salts of polyvalent metals in order that the textile surface may be rendered repellent to rain or splashed water.
Common to all these uses is that, after their treatment with the chemicals mentioned, the flat materials cannot be washed or subjected to other cleaning measures to remove any soiling. However, where the substrate is such that cleaning operations cannot be avoided, a dramatic deterioration in the water-repellent properties is always observed. This disadvantage can to some extent be compensated by refreshing the water repellency by aftertreatment with suitable hydrophobicizing agents, in which case the chemicals employed will usually have the same or similar chemical basis as the OEM finish.
On state of the art wovens, especially those composed of synthetic materials, the oil and water repellency is produced through use of water- or solvent-based FC polymers. For instance, EP-A-0 325 918 describes preparations which consist of polyurethanes modified with perfluoroaliphatic groups, and which provide good oil and water repellency on textile substrates coupled with good soft-hand and also satisfactory wash durability. EP-A-314 944 recommends formulations of FC polymers with polyethylene and modified polysiloxanes as providing a particularly smooth, soft hand.
WO 99/14422 A1 describes preparations for treatment of a fibrous substrate which, as well as FC compounds, comprise a blocked isocyanate extender, which is a reaction product of a polyisocyanate, a diol and an isocyanate-blocking agent. This blocked isocyanate extender is structurally different from component (2) claimed herein.
EP 429983 A2 describes a composition based on a perfluoroalkyl-containing polymer and an extender based on a cationically modified polyurethane which is structurally different from component (2) claimed herein.
Owing to the fact that FC formulations provide not only oil- and water-repellent effects which are durable to washing but at the same time also a good fabric hand, such compounds are currently deemed, especially with regard to use on synthetic flat materials, to be suitable products for the goal to be achieved. The disadvantage with preparations based on FC polymer is their relatively high cost, which is due to the synthesis of FC polymer involving numerous steps, some of which are energy intensive.
The altogether good overall performance level of FC polymers notwithstanding, it is to be noted that, after washing operations, there is a marked reduction in the oil- and water-repellent effect due to deorientation of the active FC moieties on the polymer molecules unless a thermal treatment is carried out to effect a reorientation. Consequently, thus treated flat materials require a heat treatment after washing in order to revitalize the desired effects. For instance, ironing or at least one tumble drying at temperatures >80° C. is a prerequisite for good regeneration of phobic properties.